Submission #949204

#	Time	Username	Problem	Language	Result	Execution time	Memory
949204		hotboy2703	Jail (JOI22_jail)	C++14	0 / 100	11 ms	10076 KiB

jail

#include<bits/stdc++.h>
using ll = long long;
using namespace std;
#define pll pair <ll,ll>
#define fi first
#define se second
#define sz(a) (ll((a).size()))
#define BIT(mask,i) (((mask) >> (i))&1)
#define MASK(i) (1LL << (i))
#define MP make_pair
ll t,n,m;
const ll MAXN = 1.2e5;
vector <ll> g1[MAXN+100];
vector <ll> g2[MAXN+100];
pll a[MAXN+100];
ll st[MAXN+100];
ll trace[MAXN+100];
bool in[MAXN+100];
bool in_st[MAXN+100];
bool detect_cycle = 0;
vector <ll> find_path(ll x,ll y){
    for (ll i = 1;i <= n;i ++)trace[i] = 0;
    trace[x] = x;
    queue <ll> q;
    q.push(x);
    while (!q.empty()){
        ll u = q.front();
        q.pop();
        for (auto v:g1[u]){
            if (!trace[v]){
                trace[v] = u;
                q.push(v);
            }
        }
    }
    ll cur=y;
//    cout<<"WOW "<<endl;
    vector <ll> res;
    do{
        res.push_back(cur);
        cur = trace[cur];
//        cout<<cur<<endl;
    }while (cur != x);
//    cout<<"WHAT "<<endl;
    reverse(res.begin(),res.end());
    return res;
}
void dfs(ll u){
    in[u] = 1;
    in_st[u] = 1;
    for (auto v:g2[u]){
        if (in_st[v])detect_cycle = 1;
        if (in[v])continue;
        dfs(v);
    }

    in_st[u] = 0;
}
int main(){
    ios_base::sync_with_stdio(0);cin.tie(nullptr);cout.tie(nullptr);
    cin>>t;
    while (t--){
        cin>>n;
        detect_cycle = 0;
        for (ll i = 1;i <= n;i ++){
            g1[i].clear();
            g2[i].clear();
            st[i] = 0;
            in[i] = in_st[i] = 0;
        }
        for (ll i = 1;i < n;i ++){
            ll u,v;
            cin>>u>>v;
            g1[u].push_back(v);
            g1[v].push_back(u);
        }
        cin>>m;
        for (ll i = 1;i <= m;i ++){
            cin>>a[i].fi>>a[i].se;
            st[a[i].fi] = i;
        }
        for (ll i = 1;i <= m;i ++){
            for (auto x:find_path(a[i].fi,a[i].se)){
                if (st[x]){
                    if (st[x] != i)g2[i].push_back(st[x]);
                }
            }
        }
//        cout<<"OK"<<endl;
        for (ll i = 1;i <= m;i ++){
            if (!in[i])dfs(i);
        }
        if (detect_cycle)cout<<"No\n";
        else cout<<"Yes\n";
    }
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 5
• Subtask 3: 0 / 16
• Subtask 4: 0 / 28
• Subtask 5: 0 / 12
• Subtask 6: 0 / 11
• Subtask 7: 0 / 23